358 The Tribological Character of LB Films of Dipalmitoylphosphatidylcholine (DPPC)

The Langmuir—Blodgett LB films of dipalmitoylphosphatidylcholine(DPPC), dipalmitoylphosphatidylcholine-arachidate(DPPC-AA) were prepared on a silicon substrate. Friction of different layers LB films on silicon surfaces was measured with Universal microtribometer (UMT) and scanning electron microscope (SEM). The DPPC LB film had lower friction as compared to the unlubricated silicon surfaces and registered much higher antiwear life and load-carrying capacity than the arachidate (AA) LB films. Meanwhile, the friction coefficient of DPPC-AA LB film/steel ball lower than that of DPPC. This would be attributed to the DPPC molecule has one more hydrophilic polar end, so the DPPC monolayer films binding more firmly to the substrate than that of AA. Meanwhile, adding arachidate (AA) to the dipalmitoylphosphatidylcholine(DPPC) could improve the quality of LB film.